The present invention relates to a motor-and-pump assembly including an electric motor with a motor housing and a pump with a pump housing, and an armature shaft with an extension which reaches into a stepped bore in the pump housing where it is retained by at least one main bearing.
An assembly of this type is disclosed in German patent application No. 42 35 962, for example. The motor housing is centered with respect to the armature shaft which is retained in the pump housing by way of a main bearing as follows:
The main bearing projects slightly from a flange surface on the pump housing. A brush support plate having a centric indentation is mounted on the bearing which projects from the flange plane. The brush support plate is thereby aligned in a radial direction relative to the projecting bearing. Further, the brush support plate has a radially outward rim onto which the housing is slipped. Thus, the motor housing is centered by way of the brush support plate, which is aligned centrically on the flange surface and, consequently, by way of the main bearing which is slipped into the pump housing.
It is easily comprehensible that the brush support plate requires intricate machining. Especially the inside rim, which abuts on the bearing, and the outside rim, on which the housing is slipped, must be manufactured with accurate tolerances relative to one another.
However, the brush support plate is a component which is generally made by injection molding. The injection molding process does not permit a high degree of precision.
Thus, a basic object of the present invention is to ensure by simple means that the motor housing is exactly aligned relative to the axis of the armature shaft.